1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and a method of driving a liquid crystal display device, and more particularly, to a liquid crystal display device including red, green, blue and white sub-pixel regions and a method of driving the same.
2. Discussion of the Related Art
Among the various types of flat panel display (FPD) devices, liquid crystal display (LCD) devices are widely used as monitors for notebook computers and desktop computers because of their excellent characteristics, such as light weight, portability and low power consumption. Specifically, active matrix type LCD devices having thin film transistors (TFTs) as switching elements have been researched and developed because of their superiority in displaying moving images.
FIG. 1 is a schematic block diagram of a liquid crystal display device according to the related art, and FIG. 2 is a schematic view showing a liquid crystal panel of the liquid crystal display device according to the related art. In FIGS. 1 and 2, the liquid crystal display device includes a liquid crystal panel 2 and a liquid crystal module (LCM) driving circuit 26. The LCM driving circuit 26 includes an interface 10, a timing controller 12, a source voltage generator 14, a reference voltage generator 16, a data driver 18 and a gate driver 20. RGB data and timing sync signals, such as clock signals, horizontal sync signals, vertical sync signals and data enable signals, are input from a driving system (not shown), such as a personal computer, to the interface 10. The interface 10 outputs the RGB data and the timing sync signals to the timing controller 12. For example, a low voltage differential signal (LVDS) interface and transistor transistor logic (TTL) interface may be used for transmission of the RGB data and the timing sync signals. In addition, the interface 10 may be integrated in a single chip together with the timing controller 12.
A plurality of gate lines “GL 1” to “GLn” and a plurality of data lines “DL1” to “DLm” are formed in the liquid crystal panel 2 and are driven respectively by the gate driver 20 and the data driver 18. The plurality of gate lines “GL1” to “GLn” and the plurality of data lines “DL1” to “DLm” cross each other to define a plurality of pixel regions. For each pixel region P, a thin film transistor “TFT” is connected to the corresponding gate line and the corresponding data line, and a liquid crystal capacitor “LC” connected to the thin film transistor “TFT” is formed in each pixel region. The liquid crystal capacitor “LC” is turned on/off by the thin film transistor “TFT,” thereby modulating the transmittance of an incident light and displaying images.
The timing controller 12 generates data control signals for the data driver 18, including a plurality of data integrated circuits (ICs), and gate control signals for the gate driver 20, including a plurality of gate ICs. Moreover, the timing controller 12 outputs data signals to the data driver 18. The reference voltage generator 16 generates reference voltages with a digital-to-analog converter (DAC) used in the data driver 18. The reference voltages are set up according to transmittance-voltage characteristics of the liquid crystal panel 2. The data driver 18 determines the reference voltages for the data signals according to the data control signals and outputs the determined reference voltages to the liquid crystal panel 2 to control a rotation angle of liquid crystal molecules.
The gate driver 20 controls the ON/OFF operation of the thin film transistors (TFTs) in the liquid crystal panel 2 according to the gate control signals from the timing controller 12. The gate driver 20 sequentially enables the plurality of gate lines “GL1” to “GLn.” Accordingly, the data signals from the data driver 18 are supplied to the pixels in the pixel regions of the liquid crystal panel 2 through the TFTs. The source voltage generator 14 supplies source voltages to elements of the LCD device and a common voltage to the liquid crystal panel 2.
FIG. 3 is a schematic view showing a pixel region of a liquid crystal display device according to the related art. In FIG. 3, a single pixel region consists of three adjacent sub-pixel regions having red, green and blue (RGB) color filters, respectively. The single pixel region displays an image using a color mixture of lights passing through the three adjacent sub-pixel regions.
To improve brightness, a liquid crystal display device including red, green, blue and white (RGBW) sub-pixel regions has been suggested. FIG. 4 is a schematic view showing a pixel region of a liquid crystal display device according to the related art. In FIG. 4, a single pixel region consists of four adjacent sub-pixel regions having red, green, blue and white (RGBW) color filters, respectively. An area ratio of RGB sub-pixel regions with respect to the single pixel region of the LCD device, including RGBW sub-pixel regions, is reduced by about 75% as compared with the LCD device including RGB sub-pixel regions. Thus, a color purity of the LCD device, including RGBW sub-pixel regions, is reduced. However, since the white sub-pixel region is operated to keep a ratio among RGB color signals and a color reproducibility range of RGB colors, the brightness of the LCD device including RGBW sub-pixel regions increases.
Each of the RGBW color filters is formed by coating, exposing and developing a resin having a respective pigment. Thus, a fabrication process of the LCD device including RGBW sub-pixel regions is complicated as compared with the LCD device including RGB sub-pixel regions. As a result, fabrication costs increase.